Heavy and cumbersome objects may need to be lifted and/or moved around garages, construction sites, farms, etc. As such, these objects may be heavy enough to require the use of equipment such as winches, hoists, or alternate pulling tools for moving and/or lifting. However, moving and hoisting equipment may be electrically operated and access to electricity may not be easily available at all sites. Accordingly, battery operable and/or externally actuatable moving and hoisting equipment may be desirable.
One example system for an externally actuatable winch is shown by Ying in U.S. Pat. No. 7,789,375. Herein, a portable winch assembly includes a planetary reduction gearbox with a primary sun gear configured to be coupled to and driven by a handheld torquing device such as an electric drill. Other than the primary sun gear, the planetary reduction gearbox further includes a first set of planet gears driven by the primary sun gear as well as a second set of planet gears driven by a secondary sun gear. The rotation of the primary sun gear and the planetary gear system enables rotation of a drum with a cable.
The inventors herein have identified potential issues with the above example system. Specifically, the portable winch assembly in U.S. Pat. No. 7,789,375 may be exposed to mechanical overload and resulting degradation. For example, torque provided by the handheld torquing device to the portable winch assembly may be amplified by the planetary reduction gearbox. The amplified torque may exceed structural design parameters of the portable winch assembly resulting in mechanical degradation of the assembly and its components. In addition, incorporating two sets of planetary gears for providing gear reduction may increase manufacturing costs of the portable winch assembly leading to higher costs for the consumer.
The inventors herein have recognized the above issues and identified various approaches to at least partly address the above issues. In one example approach, a system for a pulling tool is provided comprising a drum having an output end, an externally actuatable input shaft, an output driven shaft, a torque-limiting device positioned within the drum, the torque-limiting device including a torque-limiting mechanism situated between the externally actuatable input shaft and the output driven shaft, and a transmission including an input and a ring gear, the input coupled to the output driven shaft and the ring gear coupled to the output end of the drum. In this way, a pulling tool may be powered by external actuation while reducing incidences of torque overload.
For example, a pulling tool assembly may include a drum for winding a cable or wire rope. The drum may be positioned between a first end housing and a second end housing, and an output end of the drum may be configured with splined teeth. The drum may in turn include a torque-limiting device positioned within a spool of the drum. The torque-limiting device may include a torque limiter situated between an input drive shaft and an output driven shaft. The input drive shaft may be actuatable by an external actuator and may transmit applied torque to the output driven shaft via the torque limiter. The output driven shaft, in turn may be coupled to an input of a transmission. In one example, the input of the transmission may comprise a sun gear of a planetary gear set. Further, the transmission may include a differential planetary gear system. The transmission may further include a rotatable ring gear that meshes with the splined teeth on the output end of the winch drum. Rotational torque may be transmitted from the external actuator via the input drive shaft and output driven shaft to the transmission which in turn drives the drum to either release or retract the cable.
In this way, a pulling tool assembly may be actuated by an external device while reducing a likelihood of mechanical degradation by torque overload. By positioning the torque-limiting device between the input drive shaft and the output driven shaft, torque greater than a predetermined threshold may not be relayed to the transmission. Thus, the transmission may experience less degradation. Further, the pulling tool assembly may be operated as a handheld device as the torque-limiting device may reduce potential of torque overload. By using only a single set of differential planetary gears for torque amplification, the pulling tool assembly may have reduced manufacturing costs. Additionally, by not providing a motor within the pulling tool assembly and by using a planetary gear set and not a separate braking device, costs may be further reduced enabling the pulling tool assembly to be more affordable to a consumer.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.